This invention relates to slide connectors which connect a plurality of boards in Ell, Tee, and Cross, connections. The connection is made by the retaining slide rails affixed to the edges of the boards that has a cross section having a narrowed-down root, each of which slidably engages one of four retaining slide grooves included in four sides of a connecting bar wherein the retaining slide groove has a cross section matched to the cross section of the retaining slide rail, which includes a narrowed-down opening. The connecting bar includes at least one hole of a finite depth having a noncircular cross section disposed at at least one extremity thereof, or a through hole of a noncircular cross section disposed therethrough in a coaxial relationship with respect to the geometric center line of the cross section of the connecting bar. A threaded cylindrical locking member having an outside diameter slightly greater than the inside diameter engages the noncircular hole included in the connecting bar nd creates a small amount of distortion on the cross sectional geometry of the connecting bar, which results in a frictional locking between the connecting bar and the retaining slide rails. When the threaded cylindrical locking member is removed, the cross sectional geometry of the connecting bar returns to the original shape and the slidable engagement between the connecting bar and the retaining slide rails is restored.